Environmentally friendly fire logs

ABSTRACT

A fire log composition is provided that includes a combustible material(s), a modified plant oil(s) and a wax(es). A continuous process for the manufacture of a fire log is also provided. A fire log composition is provided that includes a combustible material, a plant oil and a wax.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to novel manufactured fire log technology. More particularly, the present invention relates to novel manufactured fire log compositions comprising renewable materials, and novel continuous processes for manufacturing the same.

BACKGROUND OF THE INVENTION

Fire logs have been used for many years as a source of heat in homes, etc. Fire logs are not only desired for the warmth they provide, but they also create a desirable cozy atmosphere. A traditional fire wood log consists of a section cut from a tree. Traditional wood logs have numerous disadvantages including but not limited to problems in relation to storage, use, emissions and disposal. For example, traditional wood logs typically are messy. The logs often leave chips of wood and bark behind. Because the logs are untidy, the logs are usually stored outside the home. Storing logs outside the home creates another disadvantage to the user, namely, the user may need to go outside to get the logs on a cold and/or inclement day. Bringing outside logs inside may create the additional disadvantage of introducing insects/pests, e.g., ants and termites into the home. Also, tradition firewood is typically very high in moisture content, particularly when stored outside or when it has been recently cut, i.e., “green”. This adds to the difficulty in lighting and burning the logs. As a result, the user is sometimes frustrated. Often, in an attempt to light the log, dangerous situations may arise, from using flammable chemicals, gasoline, or using paper products that create a dangerous situation for the user. Once lit, the traditional fire wood log needs to be monitored and frequently replaced with fresh logs to keep the fire stoked. Because traditional fire wood log fires burn at a relatively low temperature, they generate a considerable amount of undesirable emissions in the form of smoke, particulate matter and toxic chemicals such as carbon monoxide and cresols which can harm the environment and cause damage to the fireplace and flue. And when the fire is extinguished, traditional wood logs leave behind a considerable quantity of ash that has to be removed.

Heretofore known manufactured logs have solved some of the historical problems caused by the burning of traditional fire wood. Manufactured logs are neatly packaged for storage in the home, are typically easier to ignite, typically burn longer, produce significantly less emissions as compared to traditional fire logs, burn for a known duration, and produce much less ash than traditional fire wood.

Nearly all commercially available manufactured logs are composed of various types of fuel bodies formed with combustible materials that are compressed into a cylindrical or rectangular shape. For example, Yates (U.S. Pat. No. 4,179,269) discloses a log that includes ground coal. Schrader (U.S. Pat. No. 4,333,738) reports a log containing coal liquid and paraffin wax. Tutupalli et al. (U.S. Pat. No. 6,136,054) disclose a log that includes cardboard and wax. These manufactured logs have inherent environmental disadvantages, e.g., they include polluting components. For example, coal and wax products may burn incompletely, potentially discharging volatile chemicals into the atmosphere. This results in the added disadvantage of depositing volatile combustion products in the fireplace flue. These volatile build-ups may ignite later with disastrous results. Because of the seriousness of this problem, insurance companies today recommend alternating use of manufactured logs with traditional fire wood logs.

Current manufactured logs have focused on incorporating certain common waste materials into fire logs. For example, numerous waste materials have been suggested for use in modern manufactured logs, e.g., but not limited to sawdust, wood fiber, dried coffee grounds (U.S. Pat. No. 6,113,662), rice hulls or shredded paper (U.S. Pat. No. 3,297,419), ground bark and peanut shells (U.S. Pat. No. 4,040,796), grass clippings with chipped and ground branches and twigs (U.S. Pat. No. 5,393,310), and cardboard boxes (U.S. Pat. No. 6,136,054). The environmental benefits of these logs come from using waste materials, and therefore freeing-up landfill space. However, these solutions do not necessarily contribute to a cleaner burning log or hotter burning log that produces fewer emissions.

Therefore, a need exists for a manufactured log that not only utilizes common waste but renewable materials that also produces fewer emissions than traditional firewood and some manufactured logs as well.

SUMMARY OF THE INVENTION

The present invention is directed, according to one embodiment, to compositions comprising a combustible material or combustible materials and a blend, preferably a high melt point blend, comprising a modified renewable oil, preferably a plant oil, and a wax-based material(s) or a polymer(s). The preferred compositions of the present invention comprise about 50% combustible material(s) by weight of the total composition. The combustible material(s), according to one embodiment of the present invention, comprises a wood-based material, preferably comprising sawdust and/or wood flour. The blend, according to one embodiment, preferably comprises a renewable plant oil and preferably, substantially comprises a modified tall oil component. The modified tall oil is, according to an embodiment, comprised substantially of modified tall oil pitch, e.g., but not limited to tall oil pitch residue that has been saponified, neutralized, distilled, and acidulated. Note, the applicant has discovered that the sole use of an oxidized tall oil component like oxidized tall oil pitch residue, as opposed to the use of a predominantly modified tall oil component, is not desired in the practice of the present invention. While, not meant to be limited hereby, applicant believes the modified tall oil component of the present invention is advantageous over a previously oxidized tall oil component because the modified component appears to be lower in viscosity and molecular weight and thus, more readily absorbed into the combustible materials, e.g., wood fibers. A log manufactured from a tall oil component consisting substantially of an oxidized tall oil component has been found to quite often drip during burning indicating undesired free oxidized tall oil/wax blend on the surface of the fibers making it unsatisfactory for consumer use. A modified tall oil component of the present invention does not suffer from this undesired burning defect.

The wax preferably, according to one embodiment, comprises polyethylene wax. According to one embodiment of the present invention, the composition preferably comprises a ratio of oil to wax of 80:20. However, it being understood, that based upon the particular oil and/or wax combination utilized other ratios may be used in the practice of the present invention, e.g., ratios of oil to wax may include 50:50, 60:40, 75:25, 85:15, 90:10 etc.

According to one embodiment, the present invention comprises a combustible material, a modified tall oil component and a wax.

According to another embodiment of the present invention, the composition comprises at least one material selected from the group consisting of vegetable or plant flour, sawdust, wood flour or mixtures thereof; at least one modified tall oil component compound selected from the group consisting of tall oil pitch, tall oil pitch residue, crude tall oil, tall oil soap, and mixtures thereof; and at least one compound selected from the group consisting of polyethylene wax, polypropylene wax, vegetable oil esters, olefins, alpha olefins and/or mixtures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present embodiments and advantages of the embodiments of the invention may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein:

FIG. 1A illustrates a log configuration according to one aspect of the present invention;

FIG. 1B illustrates a log configuration according to one aspect of the present invention;

FIG. 2 illustrates an example of a process of the present invention; and

FIGS. 3 and 4 illustrate examples of extrusion dies that may be used in the practice of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE PRESENT INVENTION

The present invention is directed to fire log compositions comprising a combustible material or materials and a blend of a modified plant oil(s) and wax(es), preferably, a high melt point blend of the same and methods of manufacture.

The combustible materials may include any flammable substances. For example, a combustible material could, for example, be any substance of cellulosic origin such as wood or vegetable fibers. According to one embodiment of the present invention, the combustible material is sawdust. Sawdust may include any roughly or finely ground wood-based particulate matter. If sawdust is finely ground, it is then commonly referred to as wood flour. Examples of combustible materials include particulates having size diameters ranging from about 5 millimeters, for example sawdust, to about 0.15 millimeters, for example wood or vegetable flour. Some embodiments of the present invention comprise combustible materials comprising pine and mesquite tree sawdust and/or flour, but other embodiments may encompass other hard and soft woods as well.

In another embodiment of the present invention, the combustible material(s) is(are) dried before adding the same to the mixture or composition. Often, recently produced sawdust is “green.” If it contains high moisture content, it can be dried by placing in a heated environment such as an oven or a commercial dryer for a set period of time. Drying the sawdust improves the combustion nature of the sawdust by increasing the average Btu value and also improves the sawdust's ability to absorb the blend of liquid components, e.g., the oil and wax components, of the compositions, which in turn results in a mechanically stronger manufactured fire log with superior burn characteristics.

Other embodiments of the present include combustible materials that are a mixture of one or more different types of sawdust and/or wood flour as described above. For example, combustible materials may comprise a mixture of sawdust and wood flour.

According to one embodiment of the present invention, a fire log composition comprises about 50% by weight combustible material. The compositions of the present invention may comprise from about 35% to about 65% by weight combustible material(s) of the total fire log composition.

Other embodiments of the present invention may comprise a log with different ranges of combustible material(s). For example, one inventive log may comprise from about 35% to about 40% by weight combustible material of the total composition. One embodiment of the present invention may comprise from about 40% to about 45% by weight combustible material of the total composition weight. Another embodiment of the present invention may comprise from about 45% to about 50% by weight combustible material of the total weight of the composition. Other embodiments of the present invention may comprise from about 50% to about 55% by weight combustible material(s) of the total composition weight. Yet another embodiment of the present invention may include a log comprising from about 55% to about 65% by weight combustible material of the total composition weight.

An embodiment of the present invention relates to fire log compositions that include modified plant oil/oils. The plant oil(s) may be any combustible extract from a plant. The modified plant oil preferably comprises, e.g., a saponified, neutralized, distilled, and acidulated plant oil component.

In one embodiment of the present invention, the modified plant oil comprises tall oil that is typically derived from tall oil soap. Tall oil is the resinous material found in trees that includes fatty acids, rosin acids, sterols and alcohols. During the digestion phase of the wood pulping process, tall oil soap is formed on the top layer of the solution. The tall oil soap is skimmed from the digester. Typically, sulfuric acid is used to reduce the pH (a process commonly known as acidulation). This process allows for the separation of the tall oil soap from the water (tall oil soap is typically about 50% water). In one embodiment of the present invention, the modified tall oil compound component may comprise tall oil fatty acids, rosin acids, tall oil heads, crude tall oil, tall oil residue, tall oil pitch, tall oil pitch residue, and mixtures thereof. Preferably, in the practice of one embodiment of the present invention, a modified tall oil pitch residue derived from tall oil pitch is utilized. Preferably, the tall oil pitch of this embodiment is modified via saponification, neutralization, distillation, and acidulation.

The most preferred oil component, e.g., the modified tall oil pitch residue of one embodiment of the present invention is available from Chusei (U.S.A.) Inc., 12500 Bay Area Blvd., Pasadena, Tex. 77507. The most preferred modified tall oil pitch residue useful in the practice of an embodiment of the present invention comprises a mixture of long chain and tricyclic organic acids, sterols, and fatty acids (and may include, e.g., about 0-2% phosphoric acid) and has the following physical characteristics: boiling point −>280 C; softening point—approximately 40 C; specific gravity (water=1)—approximately 0.98; solubility (water)—NIL (@ 25 C); pH about 5.5 to about 7.0; vapor density (air=1)>1; physical state—liquid above 60 C; appearance & odor—dark solid, tar-like odor; flash point (COC)>250 F; acid value <40.

Using a modified tall oil component, especially a modified tall oil pitch residue, has, in accordance with one embodiment of the present invention, numerous environmental benefits. First, tall oil is a byproduct of the wood pulping process and readily available. Tall oil is a low value byproduct typically in over supply and it is often difficult to find appropriate uses for the material. A second environmental advantage of manufactured fire logs using a tall oil component, in accordance with the practice of one embodiment of the present invention, is that fewer emissions are produced compared to traditional fire wood. Due to the fact that the oil and fiber components of the present invention are derived from plants, e.g., trees, the primary components are renewable resources and thus, preferred over the use of other manufactured fire logs not employing as significant a proportion of renewable resources.

An embodiment of the present invention relates to a fire log composition that comprises a wax or waxes. The wax may comprise any low or high melting organic mixture or compound of high molecular weight. The wax may be derived from natural or synthetic sources. Natural sources may comprise waxes from animals, insects, vegetables, and mineral or petroleum sources. Synthetic sources may, e.g., comprise waxes created from petrochemical processes. The wax may comprise any isotactic, syndiotactic or atactic structures or mixtures thereof.

In one embodiment of the present invention, the wax component predominantly comprises a polyethylene wax. The polyethylene wax may comprise, e.g., high density polyethylene wax, low density polyethylene wax and/or mixtures thereof. In a particular embodiment of the present invention, the wax may comprise an oxidized wax, e.g., an oxidized polyethylene wax.

In another embodiment of the present invention, the wax component may predominantly comprises polypropylene wax. The polypropylene wax may comprise, e.g., high density polypropylene wax, low density polypropylene wax and/or mixtures thereof. In a particular embodiment, the wax is predominantly an atactic polypropylene wax.

Other embodiments of the present invention may comprise an ester or an olefin-based wax. In a particular embodiment, the wax component may comprise an alpha-olefin wax and a polyethylene wax. In a further embodiment, the ratio of oil, e.g., plant oil, to wax, e.g., an alpha olefin wax to polyethylene wax is about 90:9.5:0.5. In a preferred embodiment of the invention, the ratio of oil, e.g., plant oil, to wax, e.g., an alpha olefin wax, to polyethylene or polypropylene wax is about 80:10:10. In another embodiment of the present inventive composition, the fire log composition may comprise at least two or more waxes.

In relation to one embodiment of the present invention, the plant oil may comprise up to 80% by weight of the oil and wax blend by weight. Other embodiments of the present invention, may comprise mixtures of wax and modified plant oil ranging from about 30% to about 70% by weight of the log by weight.

According to one embodiment of the present invention, the wax is mixed with the modified plant oil in various ratios. In one embodiment, the ratio of plant oil to wax is about 19:1. In another embodiment, the ratio of modified plant oil to wax is about 4:1. The ratio of modified plant oil to wax may also be roughly equal to about 1:1. In other embodiments of the present invention, the ratio of modified plant oil to wax comprises from about 11:9 to about 19:1, however other ratios may be utilized depending upon the combustible material(s) (e.g., sawdust, flour, and mixtures) used and the state of the oil component, i.e., whether it is saponified, neutralized, distilled, and/or acidulated. Further, other ratios may be utilized depending on the wax utilized in relation to the specific modified plant oil component utilized.

The wax and modified plant oil, according to one embodiment of the present invention, may be combined to form a molten liquid blend. In one embodiment, the modified plant oil may comprise up to about 95% of the total blend by weight. In another embodiment, the plant oil may comprise up to about 80% of the blend by weight. In one embodiment, the blend comprises about 65% plant oil by weight. In another embodiment, the plant oil may comprise up to about 70% of the blend by weight. However, the amount of modified plant oil utilized man be varied depending upon the other components utilized to manufacture the fire log in accordance with various embodiments of the present invention.

According to a preferred embodiment of the present invention, a blend may comprise up to about 80% plant oil by weight of blend. Other embodiments include blends comprising plant oils by weight in the following: up to about 55% to about 60%, up to about 60% to about 65%, up to about 65% to about 70%, up to about 70% to about 75%, up to about 75% to about 80%, up to about 80% to about 85%, up to about 85% to about 90%.

One embodiment of the present invention comprises fire log compositions that further comprise an ester (or esters) or an olefin (or olefins). Esters may include acetates and carbonates such as vegetable oil esters and tall oil esters. Olefins, also referred to as alkenes, may include, e.g., any unsaturated, aliphatic hydrocarbons having one or more double bonds. In one embodiment of the present invention, the olefin component includes alpha olefins. Alpha olefins, while not meant to be limited thereby, generally tend to be considered more reactive than other olefins because of the location of the double bond.

Another embodiment of the present invention comprises fire log compositions comprising at least one compound selected from the group consisting of polyethylene wax, polypropylene wax, vegetable oil esters, olefins, alpha olefins and mixtures thereof. In a further embodiment, the inventive fire log compositions of the present invention may also comprise at least one modified compound selected from the group consisting of tall oil, crude tall oil, tall oil pitch, tall oil pitch residue, tall oil soap, and mixtures/combinations thereof.

Logs may be produced by the following process. Generally, a fire log composition is made by mixing the combustible material(s), plant oil(s) and wax(es), preferably at an elevated temperature, e.g., the temperature should typically be at least 20 F higher than the melting point of the highest melting component of the mixture Preferably, according to one embodiment, about 70 to about 100 F higher for efficient mixing. Next, the mixture is cooled (referred to herein as “pasta”) and then extruded.

The pasta is preferably produced using, e.g., a continuous, high intensity mixer and the continuous mixture is controlled at an elevated temperature (typically between about 175° F. and about 230° F.) while the combustible material(s), and the heated oil(s)/wax(es) blend are fed into the mixer on a continuous and controlled basis. The combustible material(s) is(are) preferably relatively dry, e.g., at least 80% dry (which is believed to assist in the absorption of the oil/wax mixture). In other embodiments, the combustible material(s) may be 95% dry. Preferably, the combustible material(s) is(are) below 12% moisture and most preferably below 8% moisture. Note, in relation to overall moisture of the composition, if the oil/wax blend component is not of sufficient weight, i.e., the composition is too dry, a later formed log may crack or swell upon extrusion and may undesirably break into several pieces.

The plant oil(s) need to be pre-treated before mixing with the wax(es), i.e., the tall oil component is modified. It is has been found that modifying the tall oil effects certain physical properties such as melt point and in viscosity. This has proven advantageous in the ability to continuously process the logs. Adjusting the melt point and the viscosity help allow for the production of a log that does not fall apart when being extruded and packaged or when being handled, stored and burned by the consumer.

The plant oil(s) and wax(s) are pre-mixed before added to the combustible material(s). Maintaining the wax and plant oil mixture under elevated temperature is necessary to produce a homogeneous liquid mixture prior to adding to the combustible material(s). Because it is desirable that the final log be hard at ambient temperature, it has been found advantageous to use a wax and tall oil mixture with physical properties that provide for a hard and durable fire log at ambient temperature. In one embodiment, the plant oil and wax are mixed together under elevated temperature to form a liquid mixture that quickly hardens at ambient temperature.

The combustible material(s) is(are) then mixed with the liquid. It may be preferable to mix the combustible material(s) with the liquid mixture while the liquid mixture is still hot. In one embodiment, the plant oil(s) and wax(es) are at a temperature of about 250° to about 350° Fahrenheit when the combustible material(s) is(are) added. The mixture of combustible materials, plant oils and waxes is thoroughly mixed to form a blended fire log composition also referred to as a pasta mixture.

In another embodiment, the pasta is made by mixing the plant oil(s) and about 80% of the wax(es). The combustible material(s) is(are) then added. After these ingredients have been mixed, the remaining about 20% of wax(es) is(are) added to the mixture.

The desired lengths of the log may be about 8 to about 15 inches long. The desired densities of the log may be about 45 to about 75 lbs/ft3. In a particular embodiment, pasta is extruded and a log is produced having a length of about 12 inches and a density of about 66 lbs/ft3. Because the size and density of log depends on the oil/wax/combustible material ratios in the composition of pasta, the amount of force exerted during extrusion and the design of the extrusion die may vary. Other embodiments may include other ranges of pasta, extrusion forces, and extrusion dies necessary to produce a log of about 8 to about 15 inches long and density of about 45 to about 75 lbs/ft3.

Preferably, according to an embodiment of the present invention, pasta is extruded using a single screw or twin screw extruder and an extrusion die to produce logs with grooves, e.g., V-shaped or square-shaped grooves, formed therein that is believed to improve the ease of ignition and burning performance of the log. First, the grooved log is easier to light. The grooves increase the surface area of the log allowing for more of the combustible material(s), plant oil(s) and wax(es) to be exposed. Second, the groves provide an edge or lip for improved ignition of the fire log and promote a more pleasing flame appearance while burning. Third, the longitudinal grooves also provide a path for superior flame propagation. The increased surface area and the provision of edges for flame propagation result in a log with improved ignition properties. Fourth, the grooved log burns more completely with a more consistent flame size. The increased surface area allows for better and more complete combustion of the materials of the log during the burn. This, it is believed, leads to a hotter burn. A hotter burning log allows more of the combustible material(s), plant oil(s) and wax(es) to completely burn thus, reducing emissions and the production of ash. Having the log burn hotter has the environmental benefit of reducing emissions from the combustion process.

The grooves also control the direction of the flames, allowing the log to burn more evenly and completely. The grooves guide the direction of the burning across the entire log and inward. This results in the entire log burning with little unburned material remaining. Having the log burn more evenly and completely has the additional environmental benefit of not having the user dispose of excessive unburned ash into landfills. And as mentioned, the grooved log provides a more pleasing appearance to the user while burning.

According to one embodiment of the present invention, since the plant oil(s)/wax(es) mixture or blend is of a significantly higher melting point than conventional manufactured logs, operating variables and operating costs of the extrusion process are reduced because it allows for extrusion at higher temperatures. This process according to this embodiment of the invention allows for the production of a harder, more durable log. FIGS. 1A and 1B illustrate log configurations according to exemplar embodiments of the present invention.

According to a preferred embodiment (referring to FIG. 2), the process of the present invention includes, for example, the following steps (the order of which may vary or be combined, if practical and desired):

Raw Material Addition

Wood fiber(s) (or any other combustible materials employed) is(are) mechanically conveyed from a storage silo to a weigh belt or volumetric feeder. The weigh belt feeder measures the weight (in pounds per minute and pounds per hour) of wood fiber being added into the high intensity mixer while the volumetric feeder measures the volume of a known bulk density wood fiber and converts this to weight being added into the high intensity mixer. A molten liquid blend of oil(s)/wax(es) flows from a storage tank via a heat-traced pipe into the mixer. The flow rate may be measured using a mass flow meter and the rate of addition may be ratio controlled relative to the wood fiber in order to produce a pasta of the proper combination of liquid blend and combustible material. The temperature of the molten liquid blend is controlled at about 200° F. to about 350° F. (preferably, at about 250° F. to about 350° F.), depending on the physical properties of the liquid blend and the water content of the wood fiber. If water content is higher than desired, the liquid blend is added at a higher temperature in order to remove some of the contained water by heat flashing.

Mixing

A horizontal paddle mixer may be utilized, but there are other mixers that would work as well. The wood fiber and the liquid blend are added at the same end of the continuous mixer (the feed end) in order to allow maximum residence time in the mixer to produce a consistent pasta. The mixer may be an adjustable overflow outlet weir that allows for fine tuning of the residence time in the mixer. The mixer preferrably has an external heating jacket and also can be equipped with heating for the mixer shaft and paddles. Steam is added to the jacket (and the mixing paddles if desired) in order to control the mixing temperature in a range of approximately 170° F. to approximately 250° F., preferably about 200° F. If the temperature is too high, the pasta will tend to be “wet”, indicating the liquid blend is still in the molten state, and difficult to convey and cooling of the pasta will be more difficult resulting in reduced production rates and cracking of the fire log upon extrusion. If the temperature is too low, the pasta will tend to over solidify resulting in sticking and coating of the internal surfaces of the mixer. The mixer speed and level in the mixer are controlled to provide adequate mixing intensity and to maintain adequate residence time in order to achieve a uniform pasta mix.

Cooling

The hot pasta is discharged from the mixer and via gravity, mechanical conveying, and/or pneumatic conveying flows to a continuous cooler. In the cooler, the pasta is cooled to a temperature of about 70° F. and about 130° F., preferably about 100° F., prior to extrusion. Chilled air flowing countercurrent to the pasta is preferably used for cooling. Air temperature is controlled at about 30° F. and about 60° F., preferably about 40° F., entering the cooler. Flow rate of air can be varied in order to achieve the proper pasta temperature exiting the cooler. However, too much air flow will fluidize the pasta to the point of carrying material out of the cooler with the air and overloading or plugging the cyclone. Too little air flow will result in pasta exiting the cooler at too high of a temperature and will contribute to plugging in the cooler. Therefore, air flow and temperature must be balanced to achieve adequate cooling while minimizing entrained pasta with the discharging air.

Mixer/Feeder

The cooled pasta via gravity, mechanical conveying, and/or pneumatic conveying flows from the cooler to the mixer/feeder. The function of the mixer/feeder is to provide initial compression of the pasta and additional mixing for homogeneity prior to introduction to the extruder as the material is conveyed by this equipment to the extruder. The mixer/feeder is a variable speed machine that allows a controlled feed rate to the extruder for optimum extruder operation. Additional cooling can be provided in the mixer/feeder by the direct contact of pasta with cool air or a cold gas such as carbon dioxide.

Extruder

The mixer/feeder conveys the pasta into the top of the extruder (e.g., a single screw extruder). In the extruder, pasta is compressed and pushed through the die at the exit end of the extruder (See FIGS. 3 and 4, for example). Extruder speed is controlled to provide for the desired production rate and compression. The extruder screw (via a hollow shaft), the extruder barrel and the die are temperature controlled either by heating with steam or hot water or cooling with chilled water to control the extrusion temperature. Typically, heating is used at the start-up of the extrusion process. As additional heat is generated by the extrusion process, a switch is made from heating to cooling in order to control the pasta and log temperature. Without proper temperature control, the extruder could be overloaded (caused by feeding at too low of a temperature) or logs that crack and break may be produced (caused by feeding at too high a temperature). Temperature is controlled such that the temperature of the discharging log is between about 70° F. and about 130° F., preferably about 100° F.

EXAMPLES

Both laboratory and commercial scale tests were performed to evaluate the burn characteristics of the logs. A description of the laboratory scale test stand follows: after a particular log recipe was mixed and a log was extruded according to the processes described herein, the log was subjected to a burn test. The log was lit on both bottom ends of the log. Burn characteristics were observed and noted as they occurred. Noted burn characteristics may include the ease of ignition, the flame (size and movement), heat generation, log integrity (drip or breakage), level of smoke generation, ash produced, and flame propagation. Total burn time was noted. The logs were also measured or observed in relation to total weight, log density, log durability upon handling, hardness, heat exposure, and general appearance (presence of cracks, swelling and the like).

Comparative Example I

A 2.5 pound log was produced in a single screw extruder with about 47.5% pine sawdust and 52.5% molten liquid. The liquid was composed of about 65% tall oil pitch and about 35% polyethylene wax. The tall oil pitch was oxidized to an acid value of about 20 mg KOH/g sample. The liquid blend had a heat value of about 18,055 BTU/lb. The log was lit at 8:55 a.m. At 8:58 a.m., the log was totally engulfed in flames. For the first 10 minutes, there was some dripping of liquid on the ends of the logs. At 9:21 a.m., the flames slowed to about 75% of full burn height and there was some cracking of the log on top. At 9:52 a.m., the flames were at 65% of full burn height and the log held together despite cracks. At 10:28 a.m., about one half inch of one end fell off and the log was at approximately 40% full flame. By 10:50 a.m., the flame was at about 25%. The flame was out at 11:39 a.m. The log burned for 2 hours and 44 minutes. The log still had a little unburned material in the center.

Comparative Example II

A 2.5 pound fire log was produced containing about 45% dry sawdust and about 55% molten liquid. The molten liquid was composed of about 93% oxidized tall oil pitch and about 7% polyethylene wax. The log was a slightly soft with a density of around 64 lbs/ft3 and swelled slightly when discharging from the single screw extruder. At 9:15 a.m., the log was lit, the flame spread slowly. By 9:30 a.m., the back of the log was fully lit, but not the front. Cracks started to develop on the top of the log. At 10:40 a.m., the log was out without the front ever igniting. At 10:45 a.m., the log was re-lit and in five minutes became fully engulfed. By 10:55 a.m., the log was dripping and cracking. At 11:15 a.m., the log stopped dripping and the log was burning well. At 12:00 a.m., the flame was out and the log was fully burned resulting in a total burn time of 2 hours and 45 minutes.

Exemplary Example I

A 5 pound fire log wax made of about 48% wood flour and about 52% molten liquid blend. The liquid blend was composed of about 80% modified (saponified, neutralized, distilled, and acidulated) tall oil pitch residue and about 20% polyethylene wax and had a viscosity of approximately 29 centipoise at 300 degrees Fahrenheit and a drop melt point of about 223 degrees Fahrenheit. The log was wrapped in a paper wrapper. The wrapper was lit in order to ignite the log at 6:45 a.m. The log became totally engulfed in flames at 6:50 a.m. and the log burned until 10:15 a.m.

Exemplary Example II

A 6 pound fire log was produced by extrusion and was composed of about 44% wood flour and about 56% molten liquid blend. The liquid blend was composed of about 75% modified (saponified, neutralized, distilled, and acidulated) tall oil pitch residue and about 25% polyethylene wax. The liquid blend had a viscosity of approximately 23 centipoise at 300 degrees Fahrenheit and a drop melt point of about 228 degrees Fahrenheit. The log was wrapped in a paper wrapper and at 8:30 a.m. lit by lighting the paper wrapper. The log became totally engulfed in flames by 8:37 a.m. and burned until 12:25 p.m. Flame height was very good during about 95% of the burn time. 

1. A fire log composition comprising: a combustible material; a modified plant oil; and a wax.
 2. The fire log composition of claim 1 wherein the combustible material comprises wood or vegetable fibers.
 3. The fire log composition of claim 1 wherein the plant oil comprises tall oil pitch residue.
 4. The fire log composition of claim 3 wherein the tall oil pitch residue is saponified, neutralized, distilled, and acidulated.
 5. The fire log composition of claim 1 wherein the wax comprises polyethylene wax.
 6. The fire log composition of claim 1 comprising about 50% by weight combustible material.
 7. The fire log composition of claim 1 wherein the ratio of plant oil to wax is about 19:1.
 8. The fire log composition of claim 1 wherein the ratio of plant oil to wax is about 4:1.
 9. The fire log composition of claim 1 wherein the ratio of plant oil to wax is about 1:1.
 10. The fire log composition of claim 1 wherein the ratio of plant oil to wax comprises about 1:19 to about 19:1.
 11. The fire log composition of claim 1 comprising about 35% to about 65% by weight combustible material.
 12. The fire log composition of claim 1 further comprising at least one compound selected from the group consisting of esters and olefins.
 13. The fire log composition of claim 1 wherein the wax comprises polypropylene wax.
 14. The fire log composition of claim 1 wherein the wax comprises alpha olefin wax and polyethylene wax.
 15. The fire log composition of claim 1 wherein the combustible material comprises at least one material selected from the group consisting of sawdust, wood flour, vegetable fibers, vegetable flour, and/or mixtures thereof.
 16. The fire log composition of claim 1 wherein the wax comprises at least one compound selected from the group consisting of polyethylene wax, polypropylene wax, vegetable oil esters, olefins, alpha olefins and/or mixtures thereof.
 17. The fire log composition of claim 1 wherein the plant oil comprises modified tall oil pitch residue and the wax comprises polyethylene wax.
 18. The fire log composition of claim 17 further comprising at least one other wax.
 19. A fire log composition comprising: a combustible material; a tall oil compound selected from the group consisting of modified tall oil, modified tall oil pitch, modified tall oil pitch residue, modified tall oil soap and/or mixtures thereof; and a wax.
 20. The fire log composition of claim 19 wherein the wax comprises polyethylene wax.
 21. The fire log composition of claim 19 wherein the compound is modified tall oil pitch residue, said pitch residue having been saponified, neutralized, distilled, and acidulated.
 22. The fire log composition of claim 19 wherein the log is comprised of about 50% by weight combustible material.
 23. The fire log composition of claim 19 wherein the ratio of tall oil compound to wax is about 19:1.
 24. The fire log composition of claim 19 wherein the ratio of tall oil compound to wax is about 4:1.
 25. The fire log composition of claim 19 wherein the wax comprises alpha olefin wax and polyethylene wax.
 26. The fire log composition of claim 25 wherein the ratio of tall oil compound to alpha olefin wax to polyethylene wax is about 80:10:10.
 27. A fire log composition comprising: at least one material selected from the group consisting of wood fibers, vegetable fibers, wood flours, vegetable flours and/or mixtures thereof; at least one first compound selected from the group consisting of modified tall oil pitch, modified tall oil, modified tall oil residue, modified tall oil pitch residue, modified tall oil soap, and/or mixtures thereof; and at least one second compound selected from the group consisting of polyethylene wax, polypropylene wax, vegetable oil esters, olefins, alpha olefins and/or mixtures thereof.
 28. The fire log composition of claim 27 comprising about 50% by weight of the at least one material.
 29. The fire log composition of claim 27 comprising up to about 95% first compound.
 30. The fire log composition of claim 27 comprising wood fibers or flour, modified tall oil pitch residue, and polyethylene wax.
 31. A continuous process for the production of manufactured fire logs, said process comprising: heating a wax and an oil, blending the wax with the oil to form an oil/wax blend; providing a combustible material; mixing the combustible material and the oil/wax blend to form a mixture; cooling the mixture; optionally, further mixing the cooled mixture; extruding the mixture to form an extrudate for the production of individual fire logs.
 32. A process according to claim 31, wherein the oil/wax blend is at a temperature of about 250 degrees to about 350 degrees F.
 33. A process according to claim 31, wherein the temperature is about 170 degrees F. to about 250 degrees F. during the initial mixing of the oil/wax blend and the combustible material.
 34. A process according to 31, wherein the oil/wax blend and combustible material mixture is cooled to a temperature of about 70 degrees F. to about 130 degrees F.
 35. A process according to claim 31, wherein the temperature of the extrudate is about 70 degrees F. to about 130 degrees F.
 36. A process according to claim 31, wherein the extruding step is through a die such that the extrudate has a certain shape with either square or “V” shaped grooves formed thereon.
 37. A process according to claim 31, wherein the oil component comprises saponified, neutralized, distilled, and acidulated tall oil pitch residue.
 38. A process according to claim 31, wherein the wax component comprises polyethylene wax.
 39. A process according to claim 31, wherein the combustible material comprises wood fiber. 